WCVI Sport Fishery


Assumptions and caveats to using CREST Biodata

Definitions of natural, hatchery and unknown origin Chinook:

  • A fish is assumed Natural origin if an otolith is returned as “Not Marked” and the adipose fin is intact. PBT is not currently considered as it is stock/facility-specific, and would likely only apply to very recent RYs (2022/2023).
    • This assumption may not be appropriate in cases where hatchery fish are not thermally marked AND have no other identifier (probably rare? Perhaps US?).
    • Intact adipose fins alone are NOT evidence of a natural fish, and are considered “Unknown” origin (see below)
  • A fish is Hatchery origin if it has an adipose clip, a thermal mark, a CWT, and/or a PBT BY assignment (in recent years).
    • Note there are some rare cases of wild-tagging programs in Yukon/Alaska, but these are not expected to show up in great numbers for Chinook.
  • A fish is Unknown origin if it has an intact adipose and no other mark or tag to inform further, e.g., destroyed or missing otolith, missing or lost tag, no samples analyzed, etc.)
  • Stock ID is assigned in order of reliability: CWT > PBT > Otolith > GSI


The following caveats/assumptions must be taken into consideration when interpreting the recreational fishery data presented below:

  • A genetic stock ID is only included if it has >= 75% certainty.
  • It is assumed that biosampling is representative of kept catch, but this varies year to year as sample sizes are low.
  • Biosamples represent kept, legal catch and therefore do not represent the portions of populations <45cm or >80cm
    • Only legal sized Chinook are included here (> 45cm). Extra-legal (aka Super-legal) Chinook (>80cm) have also been excluded as current regs exclude these fish from the fishery.
  • No corrections are done to account for thermal mark issues from any facility in any given year. Missing thermal marks would show up as “Not Marked” and bias results towards reporting more natural-origin Chinook than may in fact exist.
  • No GSI results are available prior to 2020 in Area 21/121.
  • Considerable changes to the recreational fishery along SWVI came into effect around 2018-2019 so comparisons across these years should be careful.
  • Unknown stock IDs were excluded from the following analyses. Results are expressed as regional population IDs as a proportion of known samples.


Please keep in mind sample rates for these areas are below ideal levels, so conclusions drawn should be very careful. Please read the last section that lays out the sample rates (i.e., % of kept catch sampled) by month and year!“



WCVI: San Juan catch across all WCVI PFMAs (27-20 and offshore)

Proportion of legal sized biosamples that return as San Juan in each Area applied to kept, legal catch estimates for 2017-2023 (note 2023 biodata still incomplete).


All San Juan-origin across WCVI

Applying stock comp %s from creel biosamples to estimated catch by Month/Area/Year. NOte 2023 is incomplete as of April 2024, and 2017-2019 lacked GSI sampling to resolve unmarked San Juan (i.e., if no thermal mark or CWT, San Juan fish would not have been detectable). 2020 onward stock ID includes otolith thermal marks, CWTs, PBT (complete BYs as of 2023 return year; PBT started BY2018), and GSI, although note not all BYs were marked completely, see https://github.com/khdavidson/A20/blob/main/outputs/R_OUT%20-%20San%20Juan%20mark%20history%20by%20BROOD%20YEAR.xlsx.



Annual monthly maps



Area 20: Area, regional IDs


Area 20: Sub-area, stock IDs